1. Field of the Invention
The present invention relates to a patch which allows the controlled release into the epidermis of at least two pharmaceutically, cosmetically or dermo-pharmaceutically active compounds, in particular compounds having different solubilities. According to the invention, this relates, in particular, to a first group of liposoluble active agents and to a second group of water-soluble active agents.
In the description of the present invention hereinbelow, the term "patch" denotes an active-agent delivery system having a composite structure in the form of layers which, when applied to the skin, ensures release of the active product by transdermal action.
As regards the liposoluble active compound, this is, in particular, a compound capable of being dissolved in an apolar medium such as an oily medium.
As regards the water-soluble active compound, it is in solid form, in particular in the form of a particulate powder or in the form of granules.
2. Description of the Prior Art
It is known to use patches which allow, by transdermal action, the penetration of active compounds.
Such patches generally have a structure containing several successive layers in the following order: a first layer, known as the support layer, which is generally occlusive, i.e. consisting of a material which is impermeable to the active compound, so as to prevent evaporation of the latter and promote the transdermal action; a second layer, known as the polymer layer, bound to the support layer and containing the active compound, it being possible for this layer to come into direct contact with the skin; optionally, in order to promote binding of the patch to the skin, a layer of an adhesive material applied to the surface of the polymer layer and permeable to the active compound; lastly, a detachable protective layer hermetically covering the polymer layer, so as to protect it against any external contamination during the storage time prior to the patch being used.
A patch structure consisting of an occlusive support layer and comprising, bound to the latter, a polymer layer made of a matrix of a silicone polymer including, in the dispersed state, fatty substances and hydrophilic active compounds, is known, in particular according to U.S. Pat. No. 5,232,702. This form of patch is more particularly suitable for delivering water-soluble active compounds and the patent does not describe the delivery of additional active compounds of lipophilic nature.
Moreover, document WO 96/14822 describes an occlusive patch of a form adapted for the treatment of wrinkles, of the abovementioned type containing a water-soluble active compound in powder form in an anhydrous matrix wherein the matrix may contain an oil, used as a penetration agent.
Furthermore, document FR-A-2,738,744 describes a patch for the controlled release of at least one cosmetically or dermo-pharmaceutically active compound, this patch containing a reservoir layer, bound to a support layer wherein the reservoir layer consists of a hydrophobic polymer matrix in which are dispersed particles of the active compound (which may be unstable in oxidizing medium) and particles of at least one water-absorbing agent, the reservoir layer being anhydrous.
A patch consisting of a silicone matrix containing a liposoluble active agent, a water- soluble active agent and an oil for increasing the penetration of the liposoluble active agent, this water-soluble active agent being in particulate form dispersed in the matrix, is also known from document DE-A-4,210,165.